I suppose most of the excitement from MacWorld Expo has died down by now, but I'd still like to talk a little about two new Mac laptops introduced at the show-- Apple's own 17" MacBook Pro, and Axiotron's Modbook Pro, a tablet computer made by repackaging the components from Apple's 15" MacBook Pro along with some new parts.

Axiotron's Modbook Pro tablet computer
Axiotron Corp.

First, the Axiotron product. Externally, the ModBook Pro is radically different from the Apple notebook that provides most of its component parts.

In this publicity photo, the Modbook Pro's beveled edges are apparent. The shape is functional, making it easier to hold the device in one hand while writing on it with the other. The shape also facilitates picking up the machine from a flat surface as well as flush-mounting the Modbook Pro in a rotating mount to create a modern version of the traditional animation desk.

The base unit of the Modbook Pro. Clockwise from lower right: the 2.5-inch hard disk, the battery, the motherboard (with I/O connectors at left and two fans for the CPU and GPU), and the optical drive.
Peter N. Glaskowsky

Inside the Modbook Pro's base unit, the original MacBook Pro components are mounted to an aluminum baseplate. The angled side pieces, machined out of a single piece of aluminum, connect that baseplate to the display and touchscreen assembly above. The result is a very solid assembly, but one that is rather heavy. The system's target weight is 6.9 pounds, though the prototype shown here was somewhat heavier. The other benefit of this assembly method is that the Modbook Pro can take any CPU-GPU combination that can go into a MacBook Pro, unlike most Windows-based Tablet PCs, which are thinner and lighter but can't handle the fastest, hottest chips. Axiotron says the Modbook Pro is the fastest tablet computer on the market (or will be, I suppose, when it ships), and as far as I know, that's true.

The new unit is scheduled to ship by June, 2009. In the meantime, Axiotron is also selling an updated version of its original Modbook, which is made from an Apple Macbook. The custom Axiotron software on the Modbook will carry over to the Modbook Pro, including the "Synergy Touch" feature which is optional on the Modbook and will be standard on the newer system. Synergy Touch provides translucent on-screen icons that can be used to control applications while the user is simultaneously drawing with the digitizer pen. It looks like an effective enhancement to the usual tablet user interface, and better for some applications than the usual combination of keyboard plus mouse or stylus.

The Modbook Pro is aimed at professional users and is priced accordingly: $4,998 and up for turnkey systems (which includes the price of the new MacBook Pro that Axiotron must buy in order to make the machine), or $3,049 and up if you send Axiotron your own MacBook Pro to be turned into a tablet.

The 17" model has the same type of milled aluminum unibody chassis introduced with the other systems in October. Like them, it also has a sheet-aluminum bottom cover. But that cover is also the first indicator of the big difference between the 17" MacBook Pro and its 15" sibling: there's no battery cover because the battery in the 17" model isn't removable.

Instead, Apple built in a 95 watt-hour lithium polymer battery featuring two kinds of new technology: new chemistry developed by Apple's own "team of scientists and electro-chemists" (according to the page on Apple.com about the 17" MacBook Pro battery) and a more advanced battery-charging circuit also developed by Apple.

I'm familiar with the basic principles of this technology from my time at Montalvo Systems, where I led the company's system architecture work. Most notebooks treat lithium batteries as if they contain just a single cell, even though internally they consist of multiple cells in series-parallel connections.

For example, the most common six-cell notebook battery arrangement is two parallel strings of three cells in series. This produces a battery with an effective output voltage around 10.8 volts (3.6V per cell times three cells, sometimes also marked as 11.1 volts depending on the average cell voltage) and twice the current capacity of a single string of cells.

(Incidentally, while I'm on the subject: please, all you OEMs, stop referring to the ampere-hour specification of an assembled battery. This is a meaningless figure without also knowing the number of cells and the average cell voltage. It's impossible to compare amp-hour figures directly. Just state the energy capacity in watt-hours. That number is far more useful.)

When such a battery is charged only through its outermost connections-- the ground and 10.8V points-- it's inevitable that one cell will become charged before the others in each string, and one string will be fully charged before the other. Eventually, some of the cells wear out before the others because of overcharging, and some cells aren't used to their full capacity because others discharge first.

Good manufacturers do the best they can to match the cells in each battery pack, but this only goes so far. This is why some battery packs will age much faster than others even though they have the same basic components-- their individual cells weren't as well matched.

In the new MacBook Pro, according to the figures on that battery page, the built-in battery pack is configured as four cells in series by two parallel strings. But the charging circuit can sample the voltages between each cell in the pack and adjust the charging current so that each cell is charged in the best possible way. Apple's website refers only to intelligent charging, but this optimization could in principle extend to the discharge side as well, allowing the power supply to cut out each cell as it becomes drained, avoiding the stress that goes with being pushed past that point.

Once Apple decided to go with this kind of charging circuit, it may have been persuaded to make the battery non-removable simply because the battery connector would have been huge-- as many as ten high-current contacts just for the cells (the two endpoints plus three internal nodes for each string of four cells) plus more for the usual temperature sensor.

Whatever the exact mechanism, Apple says that the combination of better chemistry and better charging technology gives the 17" MacBook Pro far better battery life-- and lifespan-- than other notebooks. Apple says that the model with the NVIDIA GeForce 9400M GPU can run up to 8 hours from a single charge. That corresponds to an average power consumption of less than 12 watts.

At Montalvo, I tested the power consumption of many commercially available notebook, and in my experience, 12 watts is a very good figure for a 17" system. My own 15" MacBook Pro--now a couple of years old--consumes significantly more power than that.

More significantly, Apple claims the battery in the 17" MacBook Pro can go through 1,000 full charge cycles before its capacity drops to 80% of the original figure. Since a charge cycle is the equivalent of a 100% discharge--such as two cycles to 50%, or four cycles to 75%--this specification suggests these built-in batteries should easily last five years for most users without a substantial reduction in the battery life per charge.

Of course, in real life, this potential may be reduced if the charger causes the battery to cycle slightly while the machine is plugged in. High temperatures can also reduce battery longevity. So we won't really know how effective Apple's technology is until users have had these systems for a while.

Apple users may be interested to know that the "System Profiler" application will actually report the remaining charge capacity of a battery on the Hardware, Power page. On my MacBook Pro, the original battery-- which I leave in the system essentially all the time-- now indicates a maximum charge capacity of 1,364 mAH at 10.8V, or 14.7 WH-- a decline of over 75% from the original rated capacity. System Profiler also reports that the battery's cycle count is just 61 cycles. That's probably about right, since this battery usually sustains the machine only in standby mode for the time it takes to get from home to work and back each day.

This is a far cry from the promise on Apple's website that "a properly maintained battery is designed to retain up to 80% of its original capacity at 300 full charge and discharge cycles." Perhaps that promise applies only to current systems, not my one-generation-back machine, but still, I recommend taking Apple's battery-life claims with a grain of salt.

If I were in charge of Apple's battery strategy, I would think differently. I'd fit the 17" MacBook Pro for the same removable battery found in the 15" model... and also build in a smaller battery using an entirely different battery chemistry such as lithium iron phosphate (LFP) that provides inherently longer cycle life.

An LFP battery can be charged faster than a regular lithium-polymer battery, and can have twice the cycle life when properly maintained--long enough not to be a factor in the notebook's mean time to failure.

This combination would convey the additional benefit of allowing the machine's removable battery to be swapped while it continues to operate normally, even if the user is away from an AC outlet-- a substantial advantage for business travelers. No other notebook on the market has such a feature.

I'm sure there's enough room in the 17" chassis to support such a combination. It's significantly larger than the 15" model (15% more plan area, or 21 square inches), but with essentially the same internal components. Apple says that omitting the battery packaging and retaining hardware saves a lot of space, but from my own examination of the battery compartment in a scrapped MacBook Pro case assembly, I don't think that's as big an issue as Apple says.

In this photo from the "inside" of that lower case assembly with one of my auxiliary batteries installed, you can see that the MacBook Pro battery compartment and battery casing together occupy less than a quarter of an inch around most of the battery and about a half-inch on the fourth side where the power connector is located. It adds up to a reduction in plan area of about five square inches--significant but not exactly a severe loss. Even the new 17" system must have some internal protection around the battery, if only to stop foreign objects from falling in and shorting out the cells.

Other than the battery, the new 17" MacBook Pro looks very nice, just like the earlier unibody models. Plus, it's available with an optional anti-glare display. I don't know how this effect is achieved; I've used both matte-finish displays as well as CRTs with a glass-smooth face plus an anti-reflection coating. Whichever method Apple uses, it has to be better than the high-glare effect of the standard screens on the 17" and 15" MacBook Pros. I've seen these machines in various real-world conditions now, and I just couldn't live with that level of reflectivity no matter what it does for the black levels of DVD movies.

I expect I'll be in the market for a new MacBook Pro in the coming year, and at the moment, there's no doubt in my mind--it's the new 17" for me.

About the author

Peter N. Glaskowsky is a computer architect in Silicon Valley and a technology analyst for the Envisioneering Group. He has designed chip- and board-level products in the defense and computer industries, managed design teams, and served as editor in chief of the industry newsletter "Microprocessor Report." He is a member of the CNET Blog Network and is not an employee of CNET. Disclosure.
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